2 Answers
2

You have to have that private key already. You cannot derive it from the public address. A watch-only address is an imported address.

If you've imported it from a paper wallet, check for the private key that should be printed on the same paper. You can scan the private key and upgrade the watch-only address to one that you can spend from as well.

If you imported some address you do not have the private key of, it will remain a watch-only address for you forever.

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